Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$194.52	3.328%	$200.9936	$200.99	$201.00	$201.00
Purchase #2	$165.73	10.435%	$183.0239	$183.02	$183.00	$183.00
Purchase #3	$114.98	8.616%	$124.8867	$124.89	$124.90	$124.90
Purchase #4	$18.44	10.523%	$20.3804	$20.38	$20.40	$20.40
Purchase #5	$247.42	3.378%	$255.7778	$255.78	$255.80	$255.80
Purchase #6	$119.38	5.636%	$126.1083	$126.11	$126.10	$126.10
Purchase #7	$183.26	9.530%	$200.7247	$200.72	$200.70	$200.70
7 purchase totals =	$1,043.73		$1,111.8954	$1,111.89	$1,111.90	$1,111.90